I have a 20 year old Plastimocompass on my boat and over the last few years and bubble has slowly appeared in the top. Can this be easily topped up? Does the rubber diaphram need to be changed? What sort of fluid is inside these things and assuming it is possible to do, are there any tricks?
TIA

I have a 20 year old Plastimocompass on my boat and over the last few years and bubble has slowly appeared in the top. Can this be easily topped up? Does the rubber diaphram need to be changed? What sort of fluid is inside these things and assuming it is possible to do, are there any tricks?
TIA

By all means change the diaphragm and use compass fluid, not something like whisky. Aircraft Spruce and Specialty has pint cans of fluid. It smells like solvent but it's not. Almost anything else you might use will either yellow everything inside or destroy the diaphragm.

I tried phoning all over East coastAustralia this morning to get hold of some of the fancy fluid but was not successful, so back to the web and I found on another forum someone recommend baby oil, so I got some babies and extracted the oil... just kidding, I put some baby oil in a small container and tipped in a sample of the existing stuff in the compass and it mixed fine, so I filled the compass full, put the unit in the freezer, apparently it makes the air go out of the oil and now my compass is all good again and I can re-fit it back to the back and most likely never look at it again.
Thanks for your help Guy.